WO2010DK50065 discloses a system and a method for detecting the behaviour of a number of animals, such as cattle, where each animal carries at least a number of detectors, which detectors are communicating with at least a first processor carried by the animal, which first processor further communicates with a central processor. The object of the invention is to detect animal behaviour and transmit data concerning the animal behaviour to a computer system for further analysis of the data. This object can be achieved by a system and if the system and method are further modified by letting the animal carry an accelerometer and a gyroscope for detecting movement of the animal, which system comprises at least a short-range communication system for transmitting data from the first processor to the second central processor. By using an accelerometer and a gyroscope placed at an animal, this accelerometer and gyroscope can detect the behaviour of the animal.